15 Answers

The heater in your vehicle produces heat from a heater core. The heater core is
a small radiator, located under the dashboard of the vehicle which consists of
conductive metal with cooling fins to increase surface area. Hot coolant
passing through the heater core gives off heat before returning to the engine
cooling circuit. The fan for the vehicle's ventilation system forces air through the
heater core to transfer heat from the coolant to the cabin air, which is directed
into the vehicle through the vents. If there is a lack of hot coolant running
through the heater core or (In some vehicles) the valve which opens to allow
coolant to flow into your heater core is stuck. It is crucial, however that you
immediately check the level of the antifreeze in your radiator and fill it until it is
full. Then monitor it and check for leaks. Running an engine without coolant
can lead to expensive or irreversible engine problems like head gasket failure
or broken/cracked heads or block.

Joef, yes...I've seen them in this horrific position of being "air-bound", and taken to drilling out the rivet on the t-stat, to be able to avoid the air problem, Park on a hill? but a bit disconcerting when full of coolant, yet NO HEAT- Would have to look at the condition of the coolant to see if "stuck open" is the problem- no one wants to boil a pot of water, toss in the t-stat to see at what temperature it is activated, most just replace it, because they are cheap- Back in Wisconsin, we'd simply take them out and throw them away with our fifty dollar cars-

The heater core control valve that controls the flow of coolant into the heater core
could be stuck closed, or the linkage to it is broken, not letting the water in to the
heater core. It is a cheap part. Here in Maine, we'd simply find locate the problem
and replace the part rather than guessing.

...as Berkeley's Sunday mechanic, found myself "Expert on ALL makes and models", lotsa tow-ins and folks that could not wait 'till tomorrow- Guessing was a part of the program. Stumped by a thermo-time switch on a five cylinder car learned about the importance of correct timing belt replacement. Volvos are easy, Hondas are difficult- "master of ALL makes and models" is a tough gig. Not a professional mechanic anymore, but still have all the special tools- Lucky that machine shop service was available on Sundays.

Ford, 2000. You're right. Fords do cheap out on links! There's a world of better ideas, comin' from ford..doncha know? Haven't had to service a Ford in years. Can remember the fuel pump not working, because someone ticked the bumper parking, thus engaging the "safety mode" which shuts off all high pressure fuel. Reset button was hidden behind the driver's kick panel. Kicked my ass, this problem, with no intuitive repair available.

Toyota came in with a seized up engine. The customer did not know what oil was, let alone change the oil. We added four quarts, back twisted to make sure it still turned, turned the engine on, and voila ran like new again- Toyotas can be trusted.

Would not suprise me a bit if our owner never had a coolant flush, and the existing coolant degraded to a crusty-bouldery mess which glued the t-stat open- Just a Guess, mind you, but do know about troubles thru lack of maintenance~

Haha yeah, I agree -- Ford cheaps out allot. I had a similar fuel pump problem with
my Lincoln. Well-intended feature but it causes more problems than it solves. I've
seen faulty heater core control valves allot -- specifically on Fords.

I LOVE car Gurus! turns out you are not alone in this crazy world. Now I've got a MINI! for the joy of driving! BMWs are sturdy, well made. MINIs haven't been around (since 2002) of the German made variety to exhibit major problems (though the 'permanently sealed' CVT has been troublesome for those expecting dynaflow performance) have yet to do the 30,000 $700 maintainence, drives perfectly, no compaints. Perhaps the finest car ever made.

i have came across the same problem once changed water pump thermostats and still no heat ,felt heater hoses that go to and from hear core ,and they were hot telling me there was hot water going though the heater core ,talking to some friend the advised me to check out the actuator moter and what did i find that was the problem ,it is located under the dash behind the glove compartment took it off use a pair of pliers turn it and wow i had heat, replaced it and all is good now

One of the BIGGEST issues facing Ford Owners is TEMP BLEND
DOOR ACTUATORS & DIRECTIONAL DOOR ACTUATORS. Very
Very Very COMMON problem. The Temp Blend door actuator &
sometimes the door itself will break & it will fall open allowing the a/c
to work but won't switch over to allow the heat to work. If you touch
both heater/water hoses going into the firewall near the passenger side
& they are warm/hot to the touch after running the vehicle to operating
temp, then it is definite that it's the TEMP Blend Door. It is a BIG
ORDEAL to take care of too. The entire dash must be removed.
Check out the videos on youtube. Just type in the year of your vehicle
& BLEND DOOR to see what is involved.

I have a 2003 ford expediton.. my
problem is ... my truck has to almost
over heat for me to get heat... I used
blue devil ...now it's not rising to its
level and still no heat just a little heat
.. I've change the t Stat 5 times

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